Doorknob screw



'A. M. ESTABROOK DOORKNOBi SCREW Filed Jan. 25, 1926 Aug. 24 1926. 1,597,517

INVENTOR.

411M17 Zabfoak,

ATTORNEY.

Patented Aug. 24, 1926.

W UNITED stares OFFICE.

ARCI-IIBALD M. ESTABROOK, OF HAV 'ER-HILL, IvEASSACEIUSETTS, ASSIGNORIJF tJN'E HALF TO THAD'DIEUS F. TYLER, OE HAVERHILL, MASSACHUSETTS. v

nooairnos scnnw.

Application filed January 25,1826. Serial'No. 83,709.

This invention relates to builders hardware and pertains particularly to a new type of screw designed for use in connection with door knobs.

The primary object of this invention is the provision, in a manner as hereinafter set forth, of a screw so formed that upon being forced to position a deformation will take place which will act to lock the screw against accidental loosening or misplacement.

The invention contemplates the provision of a screw designed for use in securing door knobs to their spindles, in such a manner as to prevent the screw from working loose,

and the screw is formed with one end split transversely thus setting up two ears which, when the screw is seated in the door knoc shank and extended through the spindle, will spread between the shaft and shank of the door knob and thus lock itself securely in position.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawing forming a part of this specification, with the understanding that the invention is not confined to any strict conformity with the showing of the drawing, but may be changed and modified so long as such changes and modifications mark no material departure from the salient features of the invention as expressed in the appended claim.

In the drawing Figure 1 shows a door knob .and a portion of a shaft, in side elevation, the knob shank and shaft adjacent thereto being in section to show the screw embodying this invention in position.

Figure 2 is .a transverse section taken upon line 22 of Figure 1.

Figure 3 is a detailed perspective View of the screw embodying this invention and,

Figure 4; is an enlarged side elevation of the screw embodying this invention.

Referring now to the drawing in detail wherein like numerals of reference indicate corresponding parts throughout the several views, the numeral 1 indicates a door knob of ordinary construction and having the usual shank portion 2 which is provided with a longitudinal passage 3 into which passage the lock actuating spindle 4 is adapted to have one end extended, as shown.

Extending transversely of the shank 2 and opening into the central passage 3 formed therein, is a threaded screw passage 5 into which the usual securing screw is extended to pass through .a similarly threaded passage 6 which is formed transversely through the spindle 4 adjacent one end thereof. As is well known the shank passage 3is usually of materially greater cross sectional area than is necessary to take the end of the spindle 1, and due to this manner of constructing, the screw embodying this invention is enabled to lock itself in position after having been threaded into the passages 5 and 6, as will be hereinafter described.

The screw embodying this invention is indicated by the numeral 7 .and a headless type is shown which is provided with threads throughout its length, but it is understood that a. headed screw may also be employed.

One end of this screw 7 is provided with the usual kerf 8 to receivev the end of a screw driver when the screw is being placed 1n position.

a The opposite end of the screw body 7 is transversely slotted as at 9, and the side walls .of this slotted portion are curved toward the side of the screw body, at the end of the screw .as indicated at 10 thus forming the inner end of the screw with a pair of oppositely positioned tapered tongue portions 11.. y 1

These screws are usually of soft metal construction, being usually v turned from brass and as will be readily apparent, when the screw is driven into the passages 5 and 6 and the tapered ends of the tongues 11 contact with the opposite wall of the passage 3 in the shank 2, these tongues will be forced to spread outwardly as indicated in Figure 1, forcing themselves into the slight space which is to be found between one side of the spindle 4: and the adjacent wall of the passage 3. V 7

It will thus be seen from the foregoing description that the screw 7 after having been driven into the passages 5 and 6 as shown in Figures 1 and 2, will act to lock itself in position and thus the usual annoying loosening of the door knob upon the spindle 4 due to the loosening or loss of the usual screw which holds the door knob in position upon the spindle, Will be avoided.

Having thus described my invention What I claim is In a device of the character described, including a door knob having'a shank provided With a longitudinally extending bore to receive the transversely apertured end of a shaft and further having a threaded pas sage extending through the shank and terminating 1n said bore, a screw body threaded throughout and having one end bifurcated, the furcations of said bifurcated end being each curvedupon its inner side only 15 froin the inner to the outer endsi thereof, the tips of said furcations being designed to spread laterally upon forced contactwith the inner Wall of said bore after being *eX- tended through the threaded passage and 20 

